As the film breaks box office records with an opening-weekend haul of more than $207 million, Whedon talks about what it took to get the highly-anticipated superhero team-up on screen.

After Avengers brought in a record-breaking $207 million over its opening weekend, the evidence of Joss Whedon’s suitability to bring the superhero team-up to the screen seems pretty self-evident. But the writer-director told THR that he harbored strong doubts that he could pull the film together, and it required a considerable amount of hubris to undertake the challenge in the first place.

“I think you have to have an insanely massive ego to think you can pull it off,” Whedon said. “I was out of my mind. There was many times when I was writing, when I was filming, that I thought, a grown-up should be doing this!”

Whedon said the toughest challenge he faced was to find a balance in the story where all of the characters had just enough to do. “Hard is the word,” he described. “It’s all about figuring out just enough for everyone, because too much is going to throw people, and at the same time, you don’t want to leave anybody in the cold.

“It really is just hard work figuring out structurally how they’re going to matter, how they’re going to drive the plot. But then once you’ve got that, it’s just writing the characters – and that’s fun.

While The Avengers’ success all but guarantees a follow-up from Marvel, Whedon observed that ideas he discarded as he was developing the first film would likely not be integrated into a sequel. “When an idea falls out generally speaking, it’s not because it would work better later,” he admitted. “It’s an alternate to what’s there. So I probably wrote this movie four times, and there’s some stuff I was sorry to let go of. But it’s doubtful that I would recycle it.

“The idea is always for these moments and for these humorous moments and these character moments to come from the situation they’re in at the time. Which will be different.”

Watch the video above for more comments from Whedon about his work on the blockbuster action film. The Avengers was released nationwide on Friday, May 4.